Equalizing check valve for compressors



July 5, 1949.

w. L. ECABERT 2,474,892

EQUALIZING CHECK VALVE FOR COMPRESSORS Filed Jan. 27, 1944 INVENTOR: Wa/fer L. Ember-2,

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ATTORNEYS.

Patented July 5, 1949 EQUALIZIN G CHECK VALVE FO COMPRESSORS Walter L. Ecabert, Omaha, Nebr., assignor to Baker Refrigeration Co of Nebraska moration, a corporation Application January 27, 1944, Serial No. 519,953

Claims. 1

This invention relates to refrigerationequipment and more particularly to the lubrication thereof. It is well known that proper lubrication of refrigerant compressors has been difiicult because the oil leaks from the compressor into the condensing and evaporating parts of a refrigeration system.

This difiiculty is especially true in compressors depending upon splash lubrication. In refrigeration units of this character the oil is contained in the crank case and is thrown by the cranks and connecting rods to splash the required amount of lubricant into the cylinders and onto the crank shaft, connecting rod, and wrist pin bearings. Much of the oil passes the pistons into the high pressure side of the compressor and becomes mixed with the refrigerant to circulate therewith through the entire system.

Provision is made to return this oil to the crank case by way of a connection with the suction side of the compressor, but this connection is the cause of lubrication failures when the newer types of refrigerants such as Freon, Carrene, and methyl chloride are used. These refrigerants are miscible with the lubricating oil, and, consequently, the oil does not retain its lubricating properties. In fact, the oil which returns to the crank case is reduced in gravity and may become frothy so that it is sucked directly into the suction side of the compressor and recirculated through the system. Another difficulty is that oil returned to the crank case contains refrigerant which bubbles out under suction pressures and causes the oil to froth so that it cannot be splashed to the parts to be lubricated. Moreover, the frothed oilis sucked back through the oil return connection, leaving the crank case dry.

Loss of lubricant from the crank case is not only destructible to the compressor, but it is detrimental to the other parts of the refrigerant system. The oil may congeal in the evaporating portion of the system and act to reduce refrigeration to a marked degree. The presence of oil in the system may also cause a higher condenser pressure by reason of the vapor pressure produced by the oil.

It is, therefore, the principal objects of the present invention to overcome the above difliculties; provide means for reducing contact of the refrigerating medium and oil; and to prevent compressor operating conditions that give rise to frothing of the oil, and withdrawal thereof into the refrigerant system through the suction side of the compressor.

In accomplishing these and other objects of 2 the invention, I have provided improved structure, the preferred form of which is illustrated in the accompaning drawings wherein:

Fig. 1 is a diagrammatical view of a conventional refrigerating system equipped with my invention.

Fig. 2 is a vertical sectional view through a compressor illustrating application of the present invention.

Fig. 3 is a fragmental section on the line 3--3 of Fig. 2.

Fig. 4 is a perspective view of the evaporating element forming a part of the present invention.

Referring more in detail to the drawings:

i designates a conventional refrigerating apparatus which includes a compressor 2, a condenser 3, a receiver 4, a refrigerant control valve t, an evaporating element 6, and an oil and scale trap l. The trap i is of conventional design and specifically forms no part of the present invention. It includes a casing having a cylindrical body portion la and a lateral branch 'ib connected with the intake port 2a of the compressor. The upper end of the cylindrical body is connected with a refrigerant return pipe 9 leading from the evaporating element 6. In order to prevent scale from passing to the compressor, the cylindrical body 'la of the trap contains a cylindrical screening element 'lc comprising a plurality of layers of fine mesh screen wire supported at the ends by rings let that are spaced apart by vertical stay means is located on the inner side of the screens, two of the stays being shown in vertical section in the drawing.

In operating the system a suitable refrigerant such as Freon, Carrene, and methyl chloride or the like, is contained in the receiver 4 to pass through a line 8 under control of the valve 5 for expansion in the evaporating element 6 which produces a cooling action surrounding the evaporating element. As the refrigerant expands to a gas it is drawn through a pipe 9, into the oil and scale trap 1, and is drawn directly through the screen element into the cylinder of the compressor upon the down stroke of the pistons. The refrigerant is compressed on the up stroke to be discharged through a line In into the condenser 3 where the vapor is liquified and returned to the receiver 4 completing a cycle of operation. The compressor thus divides the low and high pressure sides of the system and maintains maximum efliciency of operation-by preventing the compressed vapor from leaking back into the low pressure side of the system. It is obvious that 3 any scale carried with the refrigerant is screened out in the trap 1.

The operating parts of the compressor must, therefore, be substantially close fitting and properly lubricated at all times with an adequate quantity of lubricating oil to retard wear and supplement the seal with a minimum leakage around the compressor piston. This oil may be contained in the crankcase I I of the compressor so that it is splashed by the cranks l2 and connecting rods l3 into the cylinders and onto the bearings requiring lubrication. In practice much of the oil passes the pistons into the high pressure side of the system and is carried by the refrigerant through the line l0, condenser 3, receiver 4, line 8, valve 5, evaporating element 6,,and is returned through the suction line 9 to the trap I where it flows through the screen element at the bottom thereof into the crank case H through a connection It:

As above pointed out, the refrigerants mentioned are miscible with the oil and during this cycle the oil has collected a substantial quantity of the refrigerating medium, which, is released in the crank case since a low pressure is maintained in the crank case through its direct connection with the suction side of the compressor. The bubbling out of the refrigerating medium results in a foaming and frothing of the oil in the crank case. In fact, the oil may become so foamy and light that the foam is withdrawn through the oil return connection l4 into the suction side of the compressor and discharged through the compressor along with the refrigerating medium. Foaming of the oil in the crank case reduces the lubrication properties of the oil and the foam withdrawn results in a depletion of the lubricant supply so that the compressor runsdry.

In order to overcome this difficulty, I have provided the connection H with a circumferential seat I5 on the outlet end It thereof, which seat is preferably recessed within an annular chamber I! that is formed in the terminal face of the connection I4, as best shown in Fig. 3; the recess being of such depth that when the connection i4 is secured by bolts I8 to the oil inlet IQ of the crank case, there is ample room for play of a flap or valve 20.

The valve 20 iS best illustrated in Fig. 4 and includes a relatively thin, light-weight, disklike body 2| having an ear 22 at one side thereof provided with an opening 23 whereby the valve is slidably suspended'on a pin 24. The pin 24- may be a rivet or the like having a shank 25 driven into a socket 26 provided in the connection l4 so that the pin extends outwardly from the valve seat and parallel with the axis thereof to support the valve in closing relation with the seat when the pressures are equalized in the crank case and oil trap. The seat and valve are arranged as shown so that the valve seats by gravity and opens in response to flow of oil into the crank case. The rivet preferably has a head 2'! to limit outward movement of the valve from itsseat.

In order that the pressures may be equalized on the respective sides of the valve, the valve is provided with. a relatively small orifice or weep hole 28 as best shown in Fig. 4.

When the valve is installed and the compressor is in operation, the valve is closed incidental to the suction produced by the compressor, the pressure is equalized through the weep hole. When any oil accumulates in the trap I, the valve will open under the head thereof, and the oil will flow into the crank case of the compressor. The weep'hole is also important as it allows for withdrawal of any refrigerating vapors that escape from the returned oil while in the crank case of the compressor. Should a condition arise where the oil becomes foamy and frothy in the crank case as when an excessive amount of refrigerating vapors is contained therein, the valve will remain seated and suction of the compressor cannot effect withdrawal of the foamy oil from the crank case. When repairs are to be made in the apparatus, the crank case of the compressor is cleared of refrigerant vapors through the weep hole of the valve.

' Patent:

1. An apparatus of the character described including a refrigerant compressor having a source of lubricant supply, a refrigerant condensing and expansion apparatus respectively connected with the discharge and suction connections of the compressor, a flow connection between the suction side of the compressor and the source of lubricant supply for returning lubricant carried with the refrigeration medium circulated by the compressor to the source of lubricant supply, and a valve, means supporting the valve in the flow connection to prevent flow of lubricant in the direction of the suction connection 'of the compressor, said valve being arranged for passing vapor from said lubricant supply responsive to suction of the compressor.

2. An apparatus of the character described including a compressor having discharge and suction connections and provided with a crank case for containing a lubricant adapted to be supplied to working parts of the compressor, an oil trap connected with a suction connection of the compressor, a flow connection between the oil trap and the crank case of the compressor, and a valve normally preventin flow through the flow connection and yieldable in the direction of the crank case to pass lubricant from the oil trap to the crank case, said valve having a weep hole for establishin equalization of pressures on the respective sides thereof.

3. An oil return for a refrigerant compressor including a duct member adapted to connect the crank case of a compressor with an oil separator, a valve seat formed in said duct, a valve normally engaging said seat, and means supporting the valve for movement to and from said seat, said valve having a weep hole through which pressures are equalized on the respective sides of the valve.

4. An oil return for a refrigerant compressor including a duct member adapted to connect the crank case of a compressor with an oil separator and having a valve chamber, a seat formed in said valve chamber and encircling the flow passageway in said duct member, a pin projecting into the valve chamber substantially parallel with the axis of the seat, and a disk-like valve slidable on said pin and normally engaging said seat, said valve having a weep hole through amass:

which pressures are equalized on the respective sides of the disk-like valve.

'5. In an apparatus of the character described including a refrigerant compressor having discharge and suction connections and having a crankcase for a source of lubricant supply, a refrigerant condensing and expansion apparatus respectively connected with the discharge and suction connections of the compressor, a duct in connection with the suction connection of the compressor and discharging into the crankcase having means for, passing any refrigerant vapor from the crankcase through said flow duct to the The following references are of record in the file of this patent:

UNITED STATES PATEN'IS.

Number Name Date 1,659,104 Heidman Feb. 14, 1928 1,917,057 Pendergast July 4, 1933 2,048,025 Phillip July 21, 1936 15 2,074,323 Borgerd Mar. 23, 1937 2,127,990 Candor Aug. 23, 1938 

